Bio-compatible materials have been developed extensively and used in in vivo applications. However, bio-compatibility does not imply proper cell response upon implantation of the material. Hence a majority, if not all, of the bio-compatible materials display a certain degree of bio-inertness limiting their use and/or performance. Bio-inertness encompasses the lack of proper interaction with the host tissue, either caused by the chemically inert surface, absence of biological triggers or (bio)fouling through bulk protein absorption. This lack of proper interaction occurs rapidly upon implantation of a material and disturbs specific cell interaction. Bio-inertness has been tackled by the modification of surface architecture and topology and by incorporating bio-active ligands via covalent or non-covalent chemistry to bio-compatible materials to provoke desired cell responses. Model cell membranes, like Supported Lipid Bilayers (SLB), have shown great promise in reducing protein fouling and are tuneable in their surface composition. SLBs can be prepared via vesicle fusion and have been widely used since they were first reported (McConnel and Tamm 1985). The non-fouling nature of SLBs and their tuneable composition makes them an ideal candidate to serve as a surface coating on solid materials. However, the use of SLBs in in vivo applications has been limited.
SLBs are for example described in US2008/0241942. In this document a method for fabricating supported lipid bilayer membranes is described. The bilayer is applied on a solid surface; preferably an array. The method comprises the following steps: (i) providing a solid surface coated with a molecular film; (ii) covalently attaching sterol groups to the molecular film and (iii) contacting the sterol functionalized molecular film with a lipid solution. A disadvantage of the method described in US2008/0241942 is that a molecular film, which is for instance a hydrophilic polymer or a hydrogel coating, has to be applied to the solid surface to be able to attach a bilayer. The bilayer is not directly attached to the surface of the object, but only through the molecular film attached to the solid surface. The molecular film contains reactive groups that will covalently react with sterol groups, which will be converted into the SLB. After the reaction between sterol groups and functional groups in the molecular films, residual functional groups will be present in the hydrogel, which may destabilize the SLB, and give unwanted complications. Moreover the application of the molecular film on the support is an additional step, which is time consuming, but also adds to the complexity of the system. Not only the preparation of the SLB needs to be controlled, but also the interaction and adhesion between the substrate and the molecular film, and the stability of the molecular film. Further, the molecular film cannot be applied on all types of solid surfaces. Therefore limitations exist on the choice of substrate to be used for making a SLB. Another disadvantage is that by the application of the molecular film the chemical and mechanical properties of the solid surface are changed.
There is a need for an improved method to produce a lipid bilayer on a wide variety of bio-compatible materials.